Why do my grain jars keep getting contaminated?

Repeat grain failures usually trace to one of a few causes: sterilising time too short for the jar size, jars opened before they cooled, inoculating outside still air, or grain that was too wet. Work through them one at a time: sterilise at 15 psi for at least 90 minutes, cool fully, inoculate in a still air box with flamed tools, and hydrate grain to 45 to 55%.